An Air conditioner may include a main refrigerant circuit in which a compressor, a four-way switching valve, an outdoor heat exchanger, a main pressure-reducing valve and an indoor heat exchanger are connected in order, or a refrigeration cycle in which refrigerant is circulated. In a convention manner, the air conditioner performs the air conditioning operation e.g., a cooling operation and a heating operation, by switching a circulation direction of the refrigerant by the four-way switching valve.
However, as for the air conditioner, since the capacity of outdoor heat exchanger and the capacity of the indoor heat exchanger are different, the amount of refrigerant required for the main refrigerant circuit may vary according to the type of the air conditioning operation. Therefore, to improve the system efficiency, it may be required for the air conditioner to perform each operation with the optimized amount of refrigerant according to the type of the operation.
For this, the air conditioner has a refrigerant storage to store a surplus refrigerant. As for the air conditioner having the refrigerant storage, when the air conditioner performs an operation, in which a small amount refrigerant is needed for the main refrigerant circuit, the air conditioner may store the surplus refrigerant in the refrigerant storage. In addition, when performing an operation, in which a large amount refrigerant is needed for the main refrigerant circuit, the air conditioner may supply the refrigerant stored in the refrigerant storage to the main refrigerant circuit.
Patent document 1 discloses a refrigeration system apparatus in which a compressor, a condenser and an evaporator are installed and a receiver tank is installed between the condenser and the evaporator. Further, the patent document 1 discloses that a surplus refrigerant is collected in the receiver tank and then the refrigerant is supplied to a refrigeration cycle from the receiver tank according to the operation condition of the refrigeration system apparatus.
Patent Document 1 is disclosed in Japanese Patent Laid-Open Publication No. 10-89780.